Fix FASTQ parser

Signed-off-by: Ricky Elrod <ricky@elrod.me>
Try a `SequenceParser` typeclass idea.

This basically ends up emulating some of what Text.Trifecta.Parser
provides so it might not even be worth it. Just toying with ideas right
now.

Signed-off-by: Ricky Elrod <ricky@elrod.me>